[committed] libstdc++: Add missing runtime exception to licence notice

[Jonathan Wakely <jwakely@redhat.com>]

Tested powerpc64le-linux, pushed to trunk.

Backports to gcc-11 and gcc-12 needed too.

-- >8 --

This file is missing the GCC Runtime Library Exception text in the
licence header. That is unintentional, and it should have been present.

libstdc++-v3/ChangeLog:

	* include/std/barrier: Add missing runtime exception.
---
 libstdc++-v3/include/std/barrier | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/include/std/barrier b/libstdc++-v3/include/std/barrier
index 2a2650546ad..997e0a8f7ab 100644
--- a/libstdc++-v3/include/std/barrier
+++ b/libstdc++-v3/include/std/barrier
@@ -13,8 +13,13 @@
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.
 
-// You should have received a copy of the GNU General Public License along
-// with this library; see the file COPYING3.  If not see
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 // <http://www.gnu.org/licenses/>.
 
 // This implementation is based on libcxx/include/barrier
-- 
2.37.3